The Wang 360E is an example of Wang
Laboratories' 300-Series calculators targeted at the single-user market.
All of Wang's 300-series calculators used a modular approach, with an
electronic package that connects to remote keyboard/display
unit(s) via a cable and plug-in connection. The benefit of this method
was that the keyboard/display unit was quite small (listed in advertising
as "about the size of a desk telephone"), consuming a lot less desk space
than the monolithic "desktop" calculators of the time, such as the
Sharp Compet 20 or the
Monroe 770.
The electronic package, which could be located up to 200 feet from the
keyboard unit, contained all of the calculating brains and the power supply
for the calculating system, and the keyboard/display unit simply contained
the circuitry to drive the display and encode keypresses from the keyboard.

The Wang 300-series was an outgrowth of Wang's first generation
electronic calculator, the Wang LOCI-2.
The LOCI-2 was a bit cumbersome for non-scientific users to operate, so
Wang developed the 300-series calculator to address a wider marketplace.
The main selling point of Wang's early electronic calculators
was their ability to perform scientific functions such as logarithms and
roots, with single-key ease. Other calculators of the era could, at best,
perform a square root operation, but none could do logarithms, which are
a mainstay of scientific and engineering calculations. The only other
calculators of the time that could perform these more complex math operations
were those that were programmable, such as the Olivetti Programma 101, or the
Mathatronics Mathatron calculators. However, on these machines the
calculations would have to be performed by writing complex programs, which
required expertise to create. Plus, the programs typically would take
significant time to execute -- a natural logarithm program may take 5 to
10 seconds to generate a result using a program on one of these programmable
machines, whereas the same operation using Wang's built-in logarithm
capability would take a few hundred milliseconds. In the course of
complex engineering or scientific calculations, the time savings afforded by
Wang's logarithmic calculating capability could be very significant.

Silkscreened-on Label Identifying the Electronic Package

The 300-series calculators
were developed beginning in late 1964, and prototypes were shown at
various trade shows and conferences in the late part of 1965.
Production of the 300-series calculators began in earnest in early 1966.
The early 300-series calculators were all single-user units, with only
one keyboard/display unit connected to the electronic package. In
early 1967, Wang introduced multi-user "timeshared" (Wang called
them "Simultaneous") versions of the 300-series calculators (such as the
Wang 360SE) that would allow up to four users
to simultaneously share a single electronic package.

Because the 300-series calculators
utilized Wang's unique logarithm-generating circuitry, they were able to
perform much more complex calculations in a fraction of the time of other
calculators of the day. For this reason, the Wang 300-series calculators
started selling like hotcakes into both scientific and engineering
customer bases, propelling Wang Labs on a meteroic rise to the
top of the electronic calculator business.

The machine exhibited here is an
example of the success of Wang's 300-series. The 300-series calculators
were designed during a time when integrated circuits, which we all
take for granted today, were not a practical reality. Discrete
transistors, combined with myriad diodes, resistors, and capacitors,
make up the circuitry of all of the 300-series calculators. Even though
by late 1970, when this particular calculator was manufactured, it was
still possible for Wang to market the 300-series calculators against
those of competitors, though prime time for the sales of the 300-series
calculators was quickly nearing its end. By the time this particular
calculator was made, small-scale integrated circuits had pretty much taken
over for electronic calculator circuitry, and large-scale IC's were right
on the horizon, making shirt-pocket versions
of scientific electronic calculators a soon-to-be reality. Even though the
technology was changing rapidly, Wang had so captured the market with the
300-series calculators that they could get away with selling their "old"
all-transistor machines long after the technology was considered to be
outdated, sheerly on the inertia of the popularity of the machines.

Final Quality Assurance Sticker

The 360E exhibited here is a little bit
confusing in terms of its history. All of the internal date stamps and
codes indicate that this machine was manufactured in the late 1970 timeframe.
The final QA(Quality Assurance) sticker located inside the machine on the
backplane circuit board (see above) shows a date of December 28, 1970.
However, the pre-ship QA sticker on the outside of the machine indicates a
date of February 28, 1972! Wang Labs cranked these machines out in
prodigious volume in the late 1960's and early '70's in order
to meet customer demand. It could be that, as competition in the calculator
marketplace heated up in the early 1970's, there may have been a substantial
buildup of inventory that resulted in completed calculators sitting in
inventory for as long as 12 to 18 months before being sold and
receiving their final pre-shipment quality assurance checks.

Model/Serial Tag and Pre-Ship QA Sticker

There were five different
versions of "E" (single-user) electronic packages that were sold. The Model
300E and 310E electronics packages were the low-end of the scale, forsaking
access to the single-key scientific functions, and containing no
memory registers. The Model 320E electronics package had no memory registers,
but provided full access to the single-key scientific functions.
The 360E, and the later 362E electronic packages
added memory capabilities in the form of store/recall registers, with the
360E offering four registers, and the 362E offering twelve.
All of the E-type (single-user) electronic packages provided the same basic
arithmetic functionality, with two general-purpose
accumulators, and Wang's magical logarithm generator, embodied in another
register that accumulates logarithms. Multiplication and division, along
with scientific functions of the machines, are performed using the
logarithm generator/accumulator.

A slight diversion into the concept
of logarithms is in order here. A logarithm, simply stated, is the
'power' portion of the representation of a number in a particular base.
For example, the base ten logarithm of 1000 is 3, because 10 to the
third power is 1000. Likewise, the base ten log of 125 is 2.09691 (accurate
to five decimal places), because 10 to the 2.09691 power is roughly
125. Logarithms were the basis by which the slide rule operated, allowing
a simple device calibrated with logarithmic scales to perform multiplication
and division.

The Wang calculators don't use base
ten logarithms. Rather, they use base e logarithms. e is a
number (roughly 2.7182818) with special mathematical significance.
Using logarithms, it is possible to perform multiplication and division
by simply adding (in the case of multiplication) or subtracting (in the
case of division), the logarithms of the numbers to be multiplied or divided,
then taking the antilogarithm of the result. For example, to multiply 3
by 5, the base e logarithm of 3 is calculated (which is 1.098612,
accurate to six digits behind the decimal point), and the logarithm of
5 is calculated (1.609437), and the two logarithms added (totalling
2.708050). The antilog of this result is then calculated, resulting
in 14.999714, a result that, while not completely accurate, is
close, considering that the logarithms in this example are only stated
to 6 digits behind the decimal point. The 300-series calculators figure
logarithms accurate to 12 digits behind the decimal point, and incorporate
special rounding logic, so that multiplying 3 by 5 correctly results
in 15.00000000 rather than 14.99999998.

Along with multiplying and dividing,
the logarithm generator can be used directly for performing logarithms,
exponentials, square roots, and squaring.

Closer View of the Wang 360K Keyboard/Display Unit

The mathematical capabilities of the
electronic package are accessed by attaching a keyboard/display unit, of
which a wide range were available. See the exhibit on the
Wang 360SE for much more detail on the
300-series keyboard/display units. In short, the available keyboards were:
300K, 310K, 320K, 320KT, 320KR, 360K/362K, 360KT, and 360KR. The KR/KT
keyboards added additional internal circuitry in the form of a ROM sequencer
that executes sequences of keypresses to calculate trigonometric
functions with one keypress.

Wang 320K Keyboard with Wang CP-1 Card Reader

All of the above 300-series keyboards
could be made programmable (in a limited fashion) with the addition of the
Model CP-1 punched card reader
to allow keyboard stpes to be automated. The CP-1 allowed sequences of
keypresses to be coded onto punched cards, allowing the keypress sequences
to be 'played back' as if they were being entered from the keyboard.
This method allowed simple programs to be created. However, the CP-1
card programmer only provided limited linear programs with no looping
or branching capabilities.

Wang Model 370 and 380 Programming Keyboards

Later introductions to the
300-series calculators uncluded two truly programmable keyboard/display
units, the Model 370 and Model 380. The Model 370 keyboard/display unit
used attached punched card reader(s) (the Model 371) for programming.
Up to four card readers could be connected to the 370, allowing programs
up to 320 steps in length. The Model 380 recorded program steps onto a
removeable magnetic tape cartridge that was inserted in the back of the
keyboard/display unit. The program steps were recorded on the tape, and
'played back' to execute the program. Both the 370 and 380 keyboards
added more computer-like programming functions to the 300-series
calculators that allowed the calculators to compete with programmable
calculators from other manufacturers such as Wyle Labs, Hewlett Packard,
and others. By the late 1960's, though, it was clear that Wang's 300-series
calculators were becoming dated, and Wang began development of the
Wang 700-series calculators to respond to the
much more powerful calculators being introduced by its competition.

The Backplane of the 360E Electronic Package

The 360E electronic package is
quite a bit less complicated that the "SE" version. A total of 22 circuit
boards (versus 32 in the four-user 360SE) make up the logic of the machine.
The circuit boards plug into a printed-circuit backplane -- a contrast to
the 360SE, which uses a hand-wired
backplane. There are a total of five common circuit boards between the 360E
and the 360SE, with the rest of the boards being unique between the two
machines.

One of the Logarithm ROM Circuit Boards from the Wang 360E

A total of 491 transistors are used in
the 360E electronic package logic. It appears that the 360E electronic package
was essentially a retrofit of the 320E electronic package, adding the
additional circuitry to provide the four store/recall memory registers.
A look at the backplane of the 360E shows a curious kludge involving an
additional backplane circuit board piggybacked on the main backplane,
and a bunch of hand-wired connections that are likely related to the
memory register functionality.

The 360E Core Memory Board

The core memory subsystem is used for
storage of the calculator's arithmetic working registers, as well as for the
store/recall memory registers. This multi-function use of the core memory
subsystem reduces the complexity and component count of the machine
significantly versus the use of transistorized flip-flop registers, used in the
earlier Wang LOCI-2.

A Closeup View of the Core Memory Array

The core memory system
consists of a single board that makes up the core array and associated
sense amplifiers and inhibit drivers that interface the memory to the rest
of the electronics of the calculator. The addressing circuitry
for the core array exists on other circuit boards.
The core array in the 360E is arranged as four planes of 16 by 8 bits each,
for a total of 512 bits. This organization allows for storage
of eight 64-bit numbers.
Each register in the machine consists of 64 bits, represented
by sixteen 4-bit numbers. Digit representation is Binary-Coded Decimal
(BCD). One digit is used to represent the sign of the number. Another
digit represents the position of the decimal point within the number,
and fourteen digits represent the number itself. Ten of the fourteen
digits are displayed, with the remaining four digits used as guard
digits to increase the accuracy of the machine. Four of the eight
registers are used for the store/recall memory registers, and the remaining
four registers make up the working registers of the calculator's logic,
including the "W" (Working) register, from which the display
is generated, and into which numbers from the keyboard are entered, the
two accumulator registers, and the "L" (Logarithm) register.

Inside the 360E Electronic Package

Besides the circuit boards and backplane
of the calculator, the electronic package also contains the power supply for
the system. The power supply is a fairly basic linear power supply, with a
surprisingly small transformer, the usual assortment of large computer-grade
filter capacitors, rectifier diodes, and transistorized voltage regulation.

An original Wang Service Report and Invoice for Repairs to a Wang 360E in 1971Click Image for Larger ViewDocument Courtesy Gene McGough

The power supply provides voltages to the backplane for distribution to the
circuit boards, as well as to the remote keyboard connector, providing power
to the keyboard/display unit. It appears that somewhere along the line, Wang
added small circuit breakers to the main logic supplies. Two externally
resettable circuit breakers are installed such that it is clear that they were
an afterthought, not included in the original design of the electronic
package. I have seen earlier versions of the 300-series E-type electronics
package that do not have these circuit breakers.

An interesting side-story of the Wang 300-series calculators is the story
of the Wang 4000 Computer system. This interesting machine used the Wang 360E
as the arithmetic unit for a computer system.

Sometime in the mid 1960's, Wang's Vice President of Systems Development,
Frank Trantanella, was having a time of trying to keep up with the customized
process control and computing systems that Wang's customers were demanding.
Earlier, systems had been designed using the Wang
LOCI-2 as the main brains of the control system, with various peripherals
such as a teletype interface, analog to digital converters, and myriad
other customized (and generally one-of-a-kind) interfaces. Along with
custom hardware, the systems required completely custom programming. These
tailor-made systems were able to act as control systems for steel mills,
space suit testing systems for NASA, and other tedious or
calculation-intensive processes. The problem was that each of these
systems required pretty much a completely custom design for each different
applications that customers could dream up. Mr. Trantanella was convinced
that a more general-purpose solution could be created, and he took this
idea to heart and designed a general-purpose computer called the Wang 4000.
The Wang 4000 was based on a common data bus that allowed different
functional units (memory, arithmetic, input/output interfaces) to communicate
with each other in a consistent manner. The 4000 provided a general purpose
computing system, with standardized rack-mountable units providing the various
interfaces and processing capabilities needed. The arithmetic unit of the
4000 was composed of the electronics package of a Wang 360E electronic
calculator, just like that exhibited here. The 360E electronics
were repackaged into a rack-mount chassis, with the only addition being a
specially-designed interface board to allow the calculator logic to 'talk'
to the bus that connected the various other components of the system
together. The Model 4000 was very interesting in that it was the only computer
system at the time that had the built-in capability to perform more
complex math functions in floating point mode, such as logarithms and
roots as a native part of the instruction set of the computer. Most
computers of the time could only perform the basic four functions, some
only with integers, with much more expensive computers providing floating
point math instructions. Using the 360E electronics supplied
powerful and fast mathematical calculating ability to the 4000, making
it very easy to program for complex mathematical operations. The Model 4000,
introduced in March of 1967, sadly ended up being the victim of the success
of Wang's calculator business. Wang Labs had become immersed in the
electronic calculator business, drawing the lion's share of its revenues
from its wildly successful 300-series calculators. The resources required
to support the calculator business were being diverted from other areas of
the company, including the Systems Group headed by Mr. Trantanella. As a
result, the true capabilities of the Model 4000 Computer were never really
realized by Wang Labs, and only a few of these systems were sold. Even
though the computer was never marketed properly, the fact that it existed
is a testimony to the flexibility of design of the 300-series calculator
systems.

The K & M Electronics KM 220 Business Computer

Another example of the versatility
of the Wang 360E electronics package was a business computer developed by a
company called K & M Electronics, of Baltimore, Maryland. K & M used
Wang's 360E electronics package as the math processor for an integrated
business computer called the KM 220, introduced in May of 1968. The machine integrated the 360E
electronics package, a Teletype, a high speed paper-tape reader/punch,
a special X-Y accessible random-access magnetic strip memory system, along with
other peripheral devices into a general purposes programmable computer.
If anyone out there has any information on this amazing machine, or better yet,
may have a lead on the existence of one, I would love to hear from you.
To send the museum EMail, click HERE.

The Wang 4000 computer system and the
K & M Electronics KM 220 are just a few examples of the amazing adaptability
of the Wang 300-series calculator design. The fact that these "computers"
could be built based on electronics made to suit one need very well, that
of a high-end electronic calculator, is a testimony to the ingenuity and
foresight of Wang Labs' designs.